The Gordon Research Conference (GRC) on Barrier Function of Mammalian Skin is a biennial event, scheduled for its eleventh consecutive meeting from August 9-14, 2009 at the Waterville Valley Site in New Hampshire. This conference represents the primary international research forum on the mammalian barrier, and is focused on the biophysical, biological, and clinical aspects of both normal and diseased barrier formation and function in the epidermis. This conference is generally fully- to over-subscribed, which makes it possible to accept an optimal mix of attendees from academics, industry and government. The composition of this conference is well- mixed, with junior and senior scientists being equally represented, with approximately 40% females attendees, and 40-50% of attendees from overseas. The organizers are making a concerted effort to recruit speakers and attendees from around the world for the 2009 meeting, particularly from Eastern Europe, Asia, and Former Soviet Union countries. The 2009 conference proposes a balance of topics, with individual sessions and/or selected presentations devoted to: Molecular regulation and matrix signaling in barrier formation and regeneration;Barrier structure and function: Insights from IR, deuterium NMR, &CARS spectroscopy;Membrane lipid transport and ABC transporter proteins in lamellar body formation and skin barrier function;Protease regulation in stratum corneum structure, function, and disease;Skin biophysics and biomechanics;Skin as a psycho-sensory barrier organ;Other barriers/other worlds: lessons from GI, bile and lung barriers;Electrophysiology in barrier function;Percutaneous penetration and modeling: the Math vs. Mouse debate;Clinical dimensions of defective barriers in skin disease and repair;Anti-microbial barriers in an increasingly-hostile environment. In addition, a Hot Topics/Young Investigators session will include six-to-seven presentations selected from poster presenters. Finally, to complement the diverse themes of this meeting, three poster sessions are scheduled for the evenings, with up to 30 presentations in each session. Funds are requested from NIAMS to support a portion of the total expenses;the remainder will be supported by a $23,500 grant from the Gordon Research Conferences Foundation, with additional sums, primarily to support foreign travel as well as the minimal social activities associated with this conference, being solicited from industry. The 2009 Barrier GRC will be an important interdisciplinary venue, where the latest information and developments in this field will be presented and shared. This conference promises to provide new insights into the origin, function, maintenance, and repair of the mammalian skin barrier that will hopefully lead to immediate, practical consequences for patients with skin and other disorders.